The invention relates generally to the field of medical devices used to position and deliver therapeutic or diagnostic tools into the interior of a patient. More particularly, the invention relates to medical devices used to position and deliver a therapeutic tool to a treatment area within a patient's heart for the treatment of heart disease.
Heart disease is a significant health problem and a common cause of death. A common form of heart disease is ischemic heart disease, a condition in which parts of the heart muscle, or myocardium, do not receive an adequate supply of blood. Typically, this condition occurs when the arteries that carry blood to the myocardium become clogged by plaque build-up on their inner walls. The clogged arteries hinder blood flow, and the myocardium in the ischemic area is deprived of oxygen and other nutrients.
A number of treatments for heart disease involve direct interaction of a therapeutic tool with the wall of the heart. For example, in transmyocardial revascularization (TMR), therapeutic tools such as mechanical coring devices, lasers, or RF electrodes are used to create channels in the myocardium. The channels allow blood to flow directly from the ventricle into the ischemic area to reperfuse the tissue.
To minimize trauma to the patient, these treatments are often performed from the inside of the heart. A catheter that supports the therapeutic tool is inserted into an artery and guided through the vasculature into the heart chamber. The therapeutic tool is then used to perform the treatment on the inner wall of the heart.
For these treatments to be most effective, however, the therapeutic tool must be accurately positioned against the wall of the heart to deliver the therapy to the target location. For example, for TMR procedures, channels are made either directly into the ischemic area of the myocardium, or into the healthy tissue at the edge of the ischemic area. Therefore, the therapeutic tool used to create the channel must be placed at a location within or at the edge of the ischemic tissue. The therapeutic tool may cause unnecessary damage to healthy tissue should the therapeutic tool not be precisely placed at the target site or if the therapeutic tool lacks a substantial degree of control.
Current methods for positioning such tools can be cumbersome and imprecise. For example, U.S. Pat. No. 6,070,094 issued to Panescu et al. describes a method for positioning an ablation electrode. An array of electrodes is inserted into a heart chamber. The array is used to guide a moveable ablation electrode to a targeted site by emitting and sensing electrical and ultrasound energy. The method requires a specialized processing system that uses the sensed energy to generate an output locating the ablation electrode relative to the electrode array. A further problem is that, once the therapeutic tool is accurately placed, it must be supported and held in the proper location for the duration of the treatment. Because the heart is beating and filled with flowing blood, keeping the therapeutic tool in the proper location can be difficult. Accordingly, a device is provided for addressing the aforementioned problems.